Digital ink technology enables a user to write and draw on the touch-sensitive screen of a handheld PC or other writing tablet with a stylus or other pointing device, providing a convenient means for applications to accept input from a user without using a keyboard. For a user, taking notes or drawing sketches with using digital ink technology is very much like writing or drawing on paper.
Contemporary digital ink technology is capable of extracting a variety of information from a user's handwriting, including vector, timing, coordinates, angle of the stylus, and additional information. The digital ink information may be provided to an application, and may be used for many purposes, such as for handwriting recognition. The digital ink information may also be used for improving the way handwriting is displayed, including providing higher resolution, editing, smoothing, and alteration of individual elements, for example.
Contemporary digital ink technology is not, however, effective in generating line thickness information. Thickness information may be helpful, for example, to provide high-resolution display of calligraphy, or for font generation of some characters, such as Chinese characters. Some writing tablets have attempted to utilize pressure sensors in an effort to obtain line thickness information. However, the dynamic range of the pressure sensors in the writing tablets is limited, especially at the pressures at which people tend to write. Thus, it has been found that the pressure differentiation information provided by the existing pressure sensors is not sufficient to provide line thickness information, especially for fountain pen simulation and font generation of Chinese characters.